/*
// Licensed to Julian Hyde under one or more contributor license
// agreements. See the NOTICE file distributed with this work for
// additional information regarding copyright ownership.
//
// Julian Hyde licenses this file to you under the Apache License,
// Version 2.0 (the "License"); you may not use this file except in
// compliance with the License. You may obtain a copy of the License at:
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 */
package org.olap4j.transform;

import org.olap4j.Axis;
import org.olap4j.mdx.*;

/**
 * Abstract representation of an MDX query transform acting on a single query axis (e.g. drill-down on member, roll-up,
 * ...)
 * 
 * @author etdub
 * @since Aug 7, 2008
 */
public abstract class AxisTransform implements MdxQueryTransform {

	protected final Axis axis;

	protected AxisTransform(Axis axis) {
		this.axis = axis;
	}

	public SelectNode apply(SelectNode sn) {
		// do a deep copy of the existing query SelectNode before
		// modifying it:
		SelectNode newSelectNode = sn.deepCopy();

		for (AxisNode an : newSelectNode.getAxisList()) {
			if (an.getAxis() == axis) {
				// this is the axis we're drilling

				ParseTreeNode initialAxisExp = an.getExpression();

				// apply the drill operation
				ParseTreeNode newAxisExp = processAxisExp(initialAxisExp);

				// replace the expression in the axis by the new generated one
				an.setExpression(newAxisExp);
			}
		}
		return newSelectNode;
	}

	protected abstract ParseTreeNode processAxisExp(ParseTreeNode axisExp);

}

// End AxisTransform.java
